Photon harvesting and light trapping in pentacene and PTCDI-C13H27 for organic solar cell application

The deep understanding of optical and spectroscopic properties of organic semiconductors is essential for designing the organic photovoltaic solar cells (OSCs) and estimating their prospect performance. In this work, the optoelectronic properties of pentacene and PTCDI-C13H27 conjugated molecules were estimated using density function theory (DFT) calculations. Hence, the parameters of energy gaps, charge transfer (CT), open circuit voltage (VOC), reorganization energy and light harvesting efficiency (LHE) have been extracted using the DFT at B3LYP/6-311G(d,p) level. The results predicted that pentacene and PTCDI-C13H27 molecules possess an efficient broad-band photon harvesting over the visible spectrum with absorption maximum at 643 and 514.5 nm respectively. Moreover, the light trapping inside the pentacene and PTCDI-C13H27 layers integrated in a proposed OSC have been studied using 3D finite difference time domain (FDTD) model. The optimum thickness of the OSC layers were evaluated based on their absorption capability.